1. Field of the Invention
The present invention relates to a surface emitting device, which emits planar light by a light-guiding plate, and to a backside illumination device and a liquid crystal display device using the same.
2. Description of the Related Art
For example, in order to illuminate brightly liquid crystal display panels mounted on cellular phones, mobile game machines, and the like, a surface emitting device using a light-guiding plate with a plurality of minute grooves formed at the surface thereof (See Japanese Unexamined Patent Application Publication No. 2003-257229). The surface emitting device has a configuration in which light from a light source formed adjacent to a side end surface of a flat light-guiding plate is incident on the light-guiding plate and is emitted from a light emission surface of the light-guiding plate. For this reason, at the light emission surface, a plurality of grooves (prisms), each having an easy slope and a steep slope expending in a direction perpendicular to the incident direction of light, are formed so as to refract and emit light propagating through the light-guiding plate toward the light emission surface.
However, when the surface emitting device disclosed in Japanese Unexamined Patent Application Publication No. 2003-257229 is used to illuminate the liquid crystal display panel, there is a problem in that a moire pattern(interference fringes) occurs due to the interference between liquid crystal pixels and the minute grooves (prisms) formed at the light emission surface. Further, since the plurality of minute grooves are formed to extend in the direction perpendicular to the propagation direction of light incident from the light source, the further the distance from the light source is, the smaller the amount of light on both sides of the light-guiding plate is, which causes triangular umbrae.